Using Job Control in Shell Scripts

This tutorial provides an overview of using job control in shell scripts, allowing you to manage multiple processes and control their execution.

1. Introduction to Job Control

Job control in shell scripts refers to the ability to manage multiple processes, both in the foreground and background. It allows you to start, stop, suspend, resume, and manage processes effectively.

2. Basic Job Control Commands

Here are some basic commands used for job control:

jobs: Lists all current jobs running in the current shell.
bg: Puts a job in the background.
fg: Brings a job to the foreground.
ctrl+z: Suspends a foreground process.
kill: Terminates a job using its PID.

3. Examples of Job Control

Let's explore some examples of using job control in shell scripts:

Example 1: Running a Process in the Background

$ sleep 60 &

This command runs the sleep process in the background for 60 seconds.

Example 2: Bringing a Process to the Foreground

$ fg %1

This command brings the job with job ID 1 to the foreground.

Example 3: Suspending a Process

$ ctrl+z

This command suspends the currently running foreground process.

4. Managing Jobs

You can manage jobs by using their job IDs or process IDs (PIDs). Here are some common operations:

To list all jobs: jobs
To bring a job to the foreground: fg %job_id
To put a job in the background: bg %job_id
To kill a job: kill %job_id or kill PID

5. Conclusion

Job control is essential for managing processes effectively in shell scripts. By mastering job control commands, you can efficiently handle and monitor processes, improving script functionality and performance.